Cold work is the deforming of a material at ambient temperature, often by rolling or drawing. Drawing is the process of forcing a material to change its thickness or shape by pulling the material through a die. This causes a dense array of dislocations and disorders the material structure, resulting in an increase in yield strength and a decrease in ductility. Strengthening may occur because the large number of dislocations form dense tangles that act as obstacles to further deformation. Thus controlled amounts of cold work such as drawing can be used to vary the geometry and/or properties of the material.
Continuous drawing processes can improve the production of drawn materials by incorporating multiple draw reduction dies in series, which increases the number of reductions of the material in a given pass. A problem arises in such continuous drawing processes because the drawn material increases in speed between each reduction die as it is successively drawn. Variable drawing speeds at each draw reduction die can cause the drawn material to push and/or pull a downstream drawing apparatus. Accumulators or drums are therefore used between each drawing apparatus to take up excess material, by coiling or bending, as the material is successively drawn. In the context of drawing metal tubing, coiling of the tubing may not be possible without breaking the tubing, or at least changing dimensions of the tubing (e.g., by flattening), and bending of the tubing requires substantial space and can impart unwanted stresses on the drawn metal tubing.